大豆花叶病毒(SMV)一变异株在大豆不同抗性品种上若干特性的比较

用SMV一变异株,测定其侵染不同抗性大豆品种的侵染浓度、运转速度、显症时间及病毒浓度。结果表明;此变异株侵染感病品种合丰25的浸染度比中抗品种铁丰18低32倍,运转速度快48—96小时,侵染感病品种合丰25的显症时间显著比铁丰18短,合丰25植株体内的病毒浓度显著高于铁丰18(P<0.05)。     

品种抗性与接种棉株中大丽轮枝菌的分布及与茎切面上单孢生长的关系(续上期)

结果1.接种棉株中大丽轮枝菌的分布。接种大丽轮枝菌中等菌力非落叶型小种SS-4的抗病品种SBSI 和感病品种岱15的棉株,经过连续培养,证明该小种在其茎干组织中的分布无差异(图2A)。两品种取自茎基的切段均于接种当天产生病菌,中部切段接种后24小时产生病菌,端部切段接种后48小时产生病菌。接种后第3天,两品种各重复茎段切面上均出现了大丽轮枝菌,但观察到茎段切面上的菌丝生长及产孢活动有些差异。接种后4—5天进行抽样调查表明,感病品种岱15培养至第5或6天时产生     

花生不同发育阶段对病毒的敏感性及早播防病技术研究

本文利用田间自然接种方法,探讨了花生不同发育阶段对我国北方花生产区的三种病毒,即花生条纹病毒、黄瓜花叶病毒和花生矮化病毒的敏感性问题。研究结果表明:1、苗龄15天以下的花生幼苗最易受病毒侵染,导致严重发病,降低产量,因此这一阶段是花生感染病毒的敏感期。2、苗龄20～15天(幼苗末期至盛花期)的花生植株具有一定耐病性,感病后症状明显,但对花生结果影响较小。3、苗龄65天(结荚期)后的花生植株抗病能力明显增强,不易受病毒侵染。4、花生不同播期之间发病程度差异极显著,播种越早发病越轻。适期早播可以使花生敏感期避开蚜虫传毒高峰期。试验表明,4月15日至25日最佳播种期。     

玉米植株体内禾谷镰孢菌的PCR检测与症状对应表现分析

以高感玉米茎腐病自交系掖478为材料,用带禾谷镰孢菌牙签接种4叶期的玉米幼苗,7 d后调查接种植株,发现植株有枯萎症状和正常生长2种类型。通过特异引物对不同症状表现的植株进行PCR检测,结果表明,只有表现枯萎症状的植株体内能够检测到禾谷镰孢菌,苗期接种后仍正常生长的植株茎秆内无禾谷镰孢菌的存在。     

稻瘟病菌浅黄色素突变体对稻株诱导抗性的探讨（英文）

经用紫外光诱变菲律宾的一个具有广谱毒性的菌株PO6-6中获得2个浅黄色素突变株A和B以及从浙江省分离的弱致病性菌株C,在25/16℃、RH70%的人工气候箱内,先在4个感病品种上接种48小时后再接种强致病性菌株D和E,浅黄色素突变株和弱菌株对强菌株在水稻感病植株上呈现出交叉保护现象。6批重复试验一致表明,浅黄色素突变株和弱致病性菌株均可明显地诱导水稻植株对稻瘟病的抗病性。本文并就利用稻瘟病菌的交叉保护作用,为开辟防治新途径进行了讨论。     

旱作马铃薯氮素的吸收、积累和分配规律

马铃薯植株体内氮素浓度的高低与其生长势的强弱密切相关,本研究结果表明,叶片、地上茎、块茎中氮素浓度的变化幅度分别为2%～5%、1%～4%、1%～3%;成熟期氮素在叶片、地上茎、块茎中的分配率分别为30%左右、10%～15%、50%～60%。马铃薯对氮素的吸收速率在整个生育期间呈单峰曲线变化,峰值出现在块茎快速增长期(出苗后51d左右),最高吸收速率平均可达99 96mg/(株·d),每生产500kg块茎需吸收氮素3 02kg。     

咖啡和橡胶叶片硝酸还原酶活性诱导的研究

用体内法测定中粒种咖啡橡胶品系88—13叶片的硝酸还原酶活性,结果表明:低温干旱季节不经诱导叶片基本上不具有可测定的酶活性,但雨后则有。KNO_3诱导浓度以50毫克分子为最好。连枝叶片酶活性,橡胶以诱导36小时为最强,咖啡直到48小时酶活性仍未见下降。在室内自然光照强度和光周期条件下,酶活性随光强增加而提高,但连续光照并不能促使酶活性进一步提高。酶活性以成龄叶为最高,幼叶较低,衰老叶常不表现酶活性。100ppm 钼酸铵对咖啡和橡胶叶片酶活性都有明显的促进效应。中粒种咖啡叶片的酶活性远比橡胶品系88—13大。     

影响大豆褐斑率的若干因素

用28个大豆品种分期播种,在不同发育期接种大豆花叶病毒,探讨影向褐斑率的因素。结果表明:各品种的褐斑率与接种SMVⅠ—1、SMVⅡ—3毒株间相关显著;接种SMVⅠ—1毒株的褐斑率为66.21％,SMVⅠ—2为56.54％,SMVⅡ—3为74.45％,SMVⅡ—4为65.77％;顶枯型的褐斑率为38.1％,轻花叶型为44.1％,重花叶型为57.5％,皱花叶型为65.7％,皱缩型为81.6％。早播的褐斑率比晚播的低。真叶期接种的褐斑率较复叶期和开花期接种的低。     

NPV对不同龄期茶尺蠖的敏感性

于八六年至八七年,我们省内外收集到了三株茶尺蠖核型多角体病毒(NPV),通过筛选,得到一株毒力较高的毒株:“Bm.NPV—I”,用此毒株分别接种2—3龄,3—4龄,4—5龄三个不同龄期的幼虫,测得“Bm.NPV—Ⅰ”这一毒株对2—3龄幼虫的敏感性最强,其感染死亡率97.14％。对3-4龄幼虫的感染死亡率为 88.57％,对4—5龄幼虫的敏感性最弱,其感染死亡率为40％。     

茜草不同极性提取物的体外抑菌活性研究

本文采用k-b纸片法研究了茜草不同极性溶剂提取物的抑菌作用,结果表明,石油醚提取物浓度为50mg／ml时,抑菌率为25．03％;乙酸乙酯层提取物浓度为50mg／mL时抑制率最高,为48．64％;丙酮层提取物浓度为50mg／mL时抑制率最高,为61．59％;甲醇层提取物浓度为50mg／mL时抑制率最高,为46．09％。     

对SMV不同抗性的大豆品种体内过氧化物酶活性变化的研究

采用ＳＭＶ－ａ析系为毒源接种３人不同抗性类型的大豆品种，在接种后８，２４，４８，７小时及在３，６，９，１２，１５，１８ １１次连续取样与相应ＣＫ一并测定过氧化物酶的活性后发现：未经接种的抗感品种体内ＰＯ酶活性差异较大，病品种中ＰＯ酶活性水平高于抗性品种２倍以上。     

大豆花叶病毒（SMV）流行的产量损失及其模型预测

网室接种和田间调查测定SMV引致大豆的产量损失证明,SMV侵染大豆植株愈是在生育早期产量损失愈重。盛花期以后发病的植株产量损失显著减小,鼓粒初期的病株几乎无产量损失。SMV不同毒株引致的产量损失显著不同,强毒株的侵染,引致感病品种的产量损失平均超过弱毒株的40％。根据不同初侵染水平的30组SMV流行与产量损失数据,采用逐步回归分析,建立了准确度较高的产量损失预测多点模型和单点模型。根据损失测定,大豆盛花期的SMV病株率低于3％可控制SMV流行所造成的产量损失。     

Evaluation of common bean lines for their reaction to tomato yellow leaf curl virus-Ir2

Tomato yellow leaf curl virus (TYLCV) can cause an economically relevant disease in the major tomato growing regions, and no resistance has been identified in commercial and wild tomato cultivars in Iran. In the present study, 34 common bean lines were screened for their reaction to TYLCV-Ir2 under greenhouse conditions. The experiment was conducted in a randomized complete block design with three replications. Bean plants were inoculated at the first trifoliate stage with viruliferous whiteflies (Bemisia tabaci biotype B) and were then sprayed with an insecticide and maintained in whitefly-proof greenhouse. The inoculated plants were monitored for the development of symptoms and the presence of viral DNA by polymerase chain reaction (PCR) four weeks after inoculation. Results revealed that out of the 34 lines, five were resistant. These lines exhibited either no symptoms or very mild symptoms and no viral DNA was detected in them by PCR. Two lines, which showed no typical disease symptoms but contained viral DNA, were identified as tolerant to TYLCV-Ir2. The vector feeding preference for common bean lines was assessed. Results indicated a significant difference in adult whitefly numbers among bean lines but there was no relationship between the number of whiteflies and disease symptom severity. The resistance to TYLCY-Ir2 expressed in common bean lines may be useful as source of resistance for the development of resistant commercial common bean cultivars.     

Interactions betweenPotato leafroll virus and potato plants and their implications for assessment of infection resistance

The effects of Potato leafroll virus (PLRV) isolates and inoculation method on the resistance to PLRV in potato clones and cultivars were investigated. In the season of inoculation, aphid inoculation resulted in higher proportions of infected plants and higher virus concentration in infected plants, as compared to graft inoculation. In these respects, grafting showed superiority over aphid inoculation in the tuber progeny of inoculated plants, though distinct dominance of aphid inoculation was observed for some tested clones. This leads to the conclusion that both methods should be applied as complementary tests for the efficient selection of highly resistant potato clones. For inoculations, two isolates of PLRV were applied, and one of them, isolate L7, was routinely used in screening breeding materials for resistance to the virus. The second isolate originated from plants of the highly resistant clone DW84-1457, which were incidentally infected with PLRV. The virus isolated from these plants was able to infect only specific clones, which were resistant to isolate L7. At the same time, potato clones with resistance derived from a source different from that present in DW84-1457, and standard susceptible and resistant cultivars, showed generally lower infection ratings after inoculation with the new isolate. This result suggests that the isolates may be different strains of PLRV. It is possible that under the strong selection pressure of resistance genes present in clone DW84-1457, a new isolate I-1457 could evolve the ability to overcome resistance to infection controlled by these genes.     

Beauveria bassiana characterization and efficacy vs. Sunn pest, Eurygaster integriceps Puton (Hemiptera:Scutelleridae)

The objectives of this study were to evaluate the efficacy of Sunn pest entomopathogenic fungi collected from wheat fields and overwintering sites in Syria and characterize them under different temperature regimes. Eleven isolates of Beauveria bassiana (Bals.) Vuil. were included in this study: five were isolated from overwintered adults of Sunn Pest, Eurygaster integriceps Puton and six from nymphs and new adults in wheat fields. Growth rate and conidial production were tested at 15, 20, 25, 30 and 35 degrees C. Results showed that highest growth rate of tested fungal isolates was at 25 degrees C, except for the two isolates SPDR-1 and SPDR-2 which exhibited highest growth rate at 20 degrees C. The highest production of conidia of tested fungal isolates was at 20 degrees C, except for isolates SPSR-1, SPSQ and SPSS which exhibited higher production at 25 degrees C. Virulence test of the tested fungal isolates on overwintered adults Sunn Pest showed that percent mortality after 14 days ranged between 86-100%.     

中国北方春大豆区大豆花叶病毒株系的鉴定与分布

从我国北方春大豆区的黑龙江、吉林、辽宁、内蒙、河北承德以及北京采集典型症状的大豆叶片病样,经Top-Crop离体叶单斑分离以及DAS-ELISA抗血清免疫鉴定,共获得112个SMV阳性反应分离物.根据112个分离物在合丰25、文丰5号、诱变30、8101、铁丰25、Davis、Buffalo、早熟18、广吉、科丰1号、齐黄22共11个鉴别寄主上的症状反应,将我国北方春大豆区的SMV分成8个株系群.各株系群所占比例分析表明,北方春大豆区以SC-11株系群为主,其次为SC-8,各占病样总数的比例分别为51.7%和17.9%,SC-11和SC-8分别在黑龙江和辽宁分布最广,占当地株系群的比例分别为67.8%和75.0%.与以往株系划分系统的初步比较表明,SC-11与东北原1号株系群,SC-12和SC-16与东北原2号株系群,SC-4、SC-7、SC-8、SC-13和SC-17与东北原3号株系群在鉴别寄主上的反应相似.SC-16和SC-17为2个新发现的株系群.     

十省（区）大豆病毒毒源分析

采自５省（区）大豆病毒病样本６１份，经汁液接种鉴别寄主鉴定以及免疫双扩散测定，大豆花叶病毒（ＳＭＶ）单独侵染的样本３９份，黄瓜花叶病毒（ＣＭＶ）单独侵染的样本１２份，ＳＭＶ和ＣＭＶ复合侵染的有７份。从１０省（区）获得的大豆病毒病种子传毒率为２．７０％－１４．６８％，生物测定和血清学测定（免疫双扩散或ＥＬＩＳＡ）的种传样本４４个均为ＳＭＶ。选择各地有代表性的ＳＭＶ典型症状分离物，在电镜下观察粒子长度     

野生大豆抗花叶病毒病研究

通过对800余份野生大豆对大豆花叶病毒抗性的接种鉴定,总结出适合于野生大豆抗花叶病毒病的鉴定方法。筛选出植株抗病材料2份,中抗材料11份,其余的材料都表现中等以上的感病。植株抗性与种籽传病率有一定关系但不呈正相关,选出5份种籽传病率稳定表现为零的材料。没有发现能抗大豆花叶病毒东北三个株系的材料。探讨了野生条件下不发或很少发生花叶病毒病的原因。     

可可种质抗黑果病离体鉴定方法研究

利用可可离体叶片和离体果实鉴定可可种质对黑果病抗性的方法。结果表明：接种方法、接种物浓度、叶龄或果龄等因素影响离体叶片、果实黑果病发生程度;离体叶片接种鉴定方法最适条件是采用针刺法接种、接种物浓度3 × 107 个/mL、叶龄50～60 d;离体果实接种鉴定方法最适条件为采用滴接法、接种物浓度为3×105 个/mL、果龄2～3个月。采用离体叶片接种和离体果实接种方法均能鉴定出可可种质对黑果病抗性的差异,鉴定结果与田间成株期的抗病性表现基本一致。